Sexual Propagation & Seed GerminationTextbook pages 88 & 93

Essential Questions• How does the ability to sexually produce

seeds benefit a plant?• What is germination and what conditions are

necessary for germination to occur in a seed?

How does the ability to sexually produce seeds benefit a plant?

• Sexual reproduction in plants involves the union of the male pollen (sperm) with the female egg and results in the formation of a seed.

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Pollen + Egg = Seed

How does the ability to sexually produce seeds benefit a plant?

• Sexual reproduction enables a plant to produce new combinations of genetic information for more unique plants that may have the ability to be stronger.

Pollen + Egg = Seeds with Genetic Variation

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How does the ability to sexually produce seeds benefit a plant?

• The seed contains the embryo, the endosperm or cotyledon (the stored food), and is surrounded by a protective seed coat.

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How does the ability to sexually produce seeds benefit a plant?

• The embryo plant within the seed is the result of a fertilized egg or zygote.

• This is a combination of the genetic information from the sperm and the egg.

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Sperm + Egg = Zygote (makes the Embryo)

How does the ability to sexually produce seeds benefit a plant?

• The combination of the genetic information is called a hybrid.

• Agricultural crops have been greatly improved through hundreds of years of hybridization.

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How does the ability to sexually produce seeds benefit a plant?

• Seeds are designed to wait until the conditions are favorable to begin growth.

• The embryo plant is in a dormant or resting phase while inside the seed.

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Seeds are dormant until there are perfect conditions.

What is germination and what conditions are necessary for germination to occur in a seed?

• Germination is the end of the period of dormancy for the embryo plant.

• It occurs when the seed changes into a developing seedling.

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Germination = Seed grows into a Seedling

What is germination and what conditions are necessary for germination to occur in a seed?

• The conditions for germination are warmth, moisture, and oxygen.

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Germination = warmth, moisture, oxygen

What is germination and what conditions are necessary for germination to occur in a seed?

• Moisture - water enters the seed and causes it to expand and create pressure within the seed.

• This is called turgor pressure and causes the seed coat to rupture.

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Turgor Pressure = Ruptured Seed Coat

What is germination and what conditions are necessary for germination to occur in a seed?

• Temperature - Seeds germinate at a wide range of temperature.

• Some plants require very warm germination temperatures and other plants must have cooler temperatures.

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What is germination and what conditions are necessary for germination to occur in a seed?

• Oxygen - All seeds need oxgygen to germinate and allow growth and development of the embryo plant.

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EXIT SLIP QUESTIONS:

1) Why is sexual reproduction of plants important?

2) What is the definition of GERMINATION?

3) What conditions must be met for germination to occur?

HOMEWORK

• Write a CER summary paragraph for your Germination Cornell notes.

• Be sure to include a Claim, and support it with Evidence and Reasoning based on things that you learned today.

Tomorrow’s Content:

Two additional mechanisms affect germination in certain plant seeds:

* Stratification - a required period of cold temperature

* Scarification - a mechanism that breaks down the seed coat